package com.ruben.simplescaffold.filter;


import com.alibaba.fastjson.JSON;
import com.ruben.simplescaffold.filter.wrappers.RequestWrapper;
import com.ruben.simplescaffold.utils.sensitive.SensitiveWordUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLDecoder;
import java.nio.charset.StandardCharsets;

/**
 * 屏蔽词过滤器
 *
 * @author <achao1441470436@gmail.com>
 * @since 2021/8/6 17:10
 */
@Slf4j
@Component
@WebFilter(filterName = "SensitiveWordFilter", urlPatterns = "/**")
public class SensitiveWordFilter implements Filter {

    @Resource
    private SensitiveWordUtils sensitiveWordUtils;

    /**
     * The <code>doFilter</code> method of the Filter is called by the container
     * each time a request/response pair is passed through the chain due to a
     * client request for a resource at the end of the chain. The FilterChain
     * passed in to this method allows the Filter to pass on the request and
     * response to the next entity in the chain.
     * <p>
     * A typical implementation of this method would follow the following
     * pattern:- <br>
     * 1. Examine the request<br>
     * 2. Optionally wrap the request object with a custom implementation to
     * filter content or headers for input filtering <br>
     * 3. Optionally wrap the response object with a custom implementation to
     * filter content or headers for output filtering <br>
     * 4. a) <strong>Either</strong> invoke the next entity in the chain using
     * the FilterChain object (<code>chain.doFilter()</code>), <br>
     * 4. b) <strong>or</strong> not pass on the request/response pair to the
     * next entity in the filter chain to block the request processing<br>
     * 5. Directly set headers on the response after invocation of the next
     * entity in the filter chain.
     *
     * @param request  The request to process
     * @param response The response associated with the request
     * @param chain    Provides access to the next filter in the chain for this
     *                 filter to pass the request and response to for further
     *                 processing
     * @throws IOException      if an I/O error occurs during this filter's
     *                          processing of the request
     * @throws ServletException if the processing fails for any other reason
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
        HttpServletRequest httpServletRequest = (HttpServletRequest) request;
        long startTime = System.nanoTime();

        // 过滤
        RequestWrapper requestWrapper = new RequestWrapper(httpServletRequest, sensitiveWordUtils, null, null);
        String bodyString = RequestWrapper.BodyHelper.getBodyString(requestWrapper);
        if (log.isInfoEnabled()) {
            log.info("method:{}", requestWrapper.getMethod());
            log.info("uri:{}", requestWrapper.getRequestURI());
            log.info("parameterMap:{}", JSON.toJSONString(requestWrapper.getParameterMap()));
            log.info("bodyString:{}", bodyString);
        }

        String uri = URLDecoder.decode(requestWrapper.getRequestURI(), StandardCharsets.UTF_8.displayName());
        if (sensitiveWordUtils.isContainSensitiveWord(uri, SensitiveWordUtils.MAX_MATCH_TYPE)) {
            requestWrapper.getRequestDispatcher(sensitiveWordUtils.replaceSensitiveWord(uri, SensitiveWordUtils.MAX_MATCH_TYPE, "0")).forward(requestWrapper, response);
            return;
        }
        // 执行
        chain.doFilter(requestWrapper, response);

        if (log.isInfoEnabled()) {
            log.info("responseCode:{}", httpServletResponse.getStatus());
            log.info("timeCost:{}", (System.nanoTime() - startTime) / (1000.0 * 1000.0) + "ms");
        }
    }
}
